fix(ui): persist themes across routed surfaces

[benvinegar]

Problem

Changing the theme inside a commit review launched from history was lost when returning to the history surface. History and review each owned separate committed theme state, so only history-to-review navigation carried the active choice.

Approach

• add a session-scoped ThemeController owned by HunkSessionHost
• subscribe history and review selectors to the same committed theme identity while keeping modal previews surface-local
• remove the duplicate theme state from LogController
• retain the session launch theme as the save-preferences baseline across route remounts
• cover history-to-review-to-history navigation and repeated review launches

This belongs in core UI routing because theme selection is shared application chrome state for every routed surface, not extension-specific behavior.

Validation

• bun run typecheck
• bun run format:check
• bun run lint
• bun run deps:check
• TMPDIR=/var/tmp bun run test (4,084 passed, 12 skipped)
• bun run test:integration (157 passed, 1 skipped)
• bun run test:tty-smoke (9 passed)
• bun run install:bin
• real TTY render of hunk diff --no-extensions against the working-tree diff
• manually changed themes across history and repeated review navigation on Linux

Visual Evidence

No visual styling changes. The existing selector and themes render unchanged; this PR changes their state lifetime across route transitions.

[vercel]

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1 Skipped Deployment

Project	Deployment	Actions	Updated
hunk-web	Ignored		Sep 7, 2026 9:31pm UTC

[greptile-apps]

Greptile Summary

This PR moves committed theme ownership from individual history and review surfaces into a session-scoped controller.

• Shares committed theme changes across history-to-review route transitions and repeated review launches.
• Keeps selector previews local to each mounted surface.
• Preserves the session launch theme as the quit-time preference baseline.
• Removes duplicate theme state from LogController and adds regression coverage for controller publication and routed persistence.

Confidence Score: 5/5

The PR appears safe to merge, with routed theme ownership and preference-baseline behavior covered by focused regression tests.

No actionable correctness, security, or repository-rule violations remain; the shared controller preserves launch-scoped theme detection and uses the same theme catalog across the normal history-to-review flow.

Important Files Changed

Filename	Overview
packages/hunk/src/ui/theme/controller.ts	Introduces a small session-scoped external store for the resolved launch theme and subsequent committed identities.
packages/hunk/src/ui/hooks/useThemeSelectorController.ts	Replaces surface-local committed theme state with a subscription to the shared controller while retaining local modal preview state.
packages/hunk/src/ui/session/HunkSessionHost.tsx	Owns one theme controller across routed history and review surfaces and forwards its current theme when preparing reviews.
packages/hunk/src/ui/log/LogApp.tsx	Uses the shared theme controller and removes theme details from the route outcome contract.
packages/hunk/src/ui/App.tsx	Consumes an injected session theme controller with a standalone fallback and uses its launch identity as the preference baseline.
packages/hunk/src/ui/session/HunkSessionHost.test.tsx	Covers theme persistence through history, repeated review launches, return navigation, and preference prompting.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    Session[HunkSessionHost] --> Controller[ThemeController]
    Controller --> History[LogApp theme selector]
    Controller --> Review[AppHost / App theme selector]
    History -->|commitTheme| Controller
    Review -->|commitTheme| Controller
    Controller -->|external-store snapshot| History
    Controller -->|external-store snapshot| Review
    History -->|launch review with current theme| ReviewRoute[Embedded review route]
    ReviewRoute -->|quit| History

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